Downlink (DL) and uplink (UL) joint communication and sensing (JCAS) technologies have been individually studied for realizing sensing using DL and UL communication signals, respectively. Since the spatial environment and JCAS channels in the consecutive DL and UL JCAS time slots are generally unchanged, DL and UL JCAS may be jointly designed to achieve better sensing performance. In this paper, we propose a novel DL and UL cooperative (DUC) JCAS scheme, including a unified multiple signal classification (MUSIC)-based JCAS sensing scheme for both DL and UL JCAS and a DUC JCAS fusion method. The unified MUSIC JCAS sensing scheme can accurately estimate AoA, range, and Doppler based on a unified MUSIC-based sensing module. The DUC JCAS fusion method can distinguish between the sensing results of the communication user and other dumb targets. Moreover, by exploiting the channel reciprocity, it can also improve the sensing and channel state information (CSI) estimation accuracy. Extensive simulation results validate the proposed DUC JCAS scheme. It is shown that the minimum location and velocity estimation mean square errors of the proposed DUC JCAS scheme are about 20 dB lower than those of the state-of-the-art separated DL and UL JCAS schemes.

翻译：下行与上行联合通信与感知技术已分别被研究，用于利用下行和上行通信信号实现感知功能。由于连续下行和上行JCAS时隙中的空间环境及JCAS信道通常保持不变，因此可联合设计下行与上行JCAS以实现更优的感知性能。本文提出一种新颖的下行与上行协作JCAS方案，包括基于统一多重信号分类的JCAS感知方案（适用于下行与上行JCAS）以及一种DUC JCAS融合方法。该统一MUSIC JCAS感知方案基于统一的MUSIC感知模块，可精确估计到达角、距离及多普勒频移。DUC JCAS融合方法能够区分通信用户与其他无源目标的感知结果，并通过利用信道互易性提升感知精度及信道状态信息估计准确度。大量仿真结果验证了所提DUC JCAS方案的有效性。实验表明，与当前最优的分离式下行与上行JCAS方案相比，所提方案的位置与速度估计最小均方误差降低了约20 dB。